Refractive errors and its correction.
If you have to wear glasses or contact lenses to have a clear vision then probably you have a refractive error. In this situation the light rays do not come to focus on the back part of the eye (retina).
1. Myopia (Short-sightedness or Near-sightedness)
The myopic eye is longer than normal and distant images are focused in front of the retina instead of on it, causing a blurred image. Someone with myopia will see near objects clearly, but distant objects will be blur.
2. Hyperopia (Long-sightedness or Far-sightedness)
The hyperopic eye is shorter than normal and images are focused behind the retina, leading to a blurred image. Someone with hyperopia will see distant objects clearly but objects that are nearby will be blur.
The astigmatic cornea is unevenly curved, resulting in blurred and multiple distorted images. This affects distant and near objects equally. Astigmatism may co-exist with myopia or hyperopia.
4. Presbyopia (Old-sightedness)
In presbyopia, the eye loses its ability to focus on near objects. It is caused by ageing and usually begins around 40 years of age. With time, presbyopia will progress and worsen, necessitating reading glasses. LASIK cannot prevent or correct presbyopia.
There are many ways to correct refractive errors:
- Spectacles though common can be inconvenient and cosmetically unacceptable to some people. They restrict peripheral vision and can interfere with sports and outdoor activities.
- Contact Lenses
- Contact lenses allow for more freedom during sports and other activities, and maximize peripheral vision. However, they can be troublesome to maintain, expensive in the long term, and carry a risk of infection.
- Refractive Surgery
- Refractive surgery changes the focusing power of the eye by altering the shape of the cornea, usually permanently. Laser vision correction is one form of refractive surgery, of which Laser Assisted In-Situ Keratomileusis (LASIK) is the most common form.
- Implant Refractive Surgery
- Most refractive errors can be corrected by LASIK except for the very high refractive errors. In this situation, Phakic Intraocular Lens (IOL) can be considered. Unlike LASIK, which modifies the shape of the cornea, Phakic IOL is an artificial lens that is surgically implanted into the eye in front of the patient's natural lens and works like a contact lens within the eye.
Who Is Suitable For LASIK /LASEK?
· You should be at least 18 years of age.
· Your glass power should be stable .
· You should not have eye problems such as cataracts, glaucoma or keratoconus.
A comprehensive eye examination before surgery is required to assess your suitability for LASIK. You'll have ample opportunity to discuss all aspects of the surgery with your surgeon.
Before the first consultation.
Prior to your LASIK assessment, you are requested to stop contact lens wear.
The minimum recommended time to stop contact lens wear:
- Soft Contact Lenses :1 week before assessment / surgery
- Rigid Gas Permeable Lenses : 2 weeks before assessment / surgery
This is to ensure the accuracy of the results obtained during your LASIK assessment.
Preoperative Lasik Assessment
During your LASIK assessment, a series of eye examinations will be performed. These include the following:
1. Visual acuity test(vision assessment)
2. Estimation of Intra Ocular Pressure
3. Refraction: Eye drops will be instilled to obtain a precise measurement of your eye power
4. Slit lamp examination of your eyes
5. Dilated fundus examination( Retina examination)
6. Pachymetry(corneal thickness measurement)
7. Corneal topography(to assess the front surface of the eye)
8. Wavefront analysis (to assess any optical aberrations)
9. Pentacam analysis of the total cornea.
After the tests, your surgeon will then decide whether you are suitable for LASIK /LASEK. fake rolex, replica rolex, luxury replica watches, fake rolex watches
Step 1: Create the flap in the front of the cornea with the flap still attached on a hinge.
Step 2: The corneal flap is folded to the side, and the excimer laser is applied on the cornea to correct the refractive error.
Step 3: The corneal flap is then replaced to cover the area removed by the laser.
The operation will be performed under topical anaesthesia that is eyedrops will be used to numb your eyes. An eyelid instrument will be used to gently open your eye to prevent it from blinking.
During the fashioning of the corneal flap, your vision will be momentarily dimmed. This takes only 20 seconds. You may feel a slight pressure sensation but there will be no pain.
Next, the Excimer laser will be applied to reshape the cornea, which takes approximately 30 to 60 seconds. You are required to stare at a fixating light during the laser ablation and remain still. Again, there will be no pain.
Follow up after Surgery
Your surgeon will review you the following day and then after 1 week, 1 month and 3 months from the date of surgery. It is important to follow the post-operative advice and to use the eyedrops as instructed.